Generally, when amphiphilic block copolymers are dissolved in a solvent which is selective for only one of the blocks, nanosized aggregates form due to the self-assembly of the less soluble segment. The term “water-soluble associating polymer” is given to those polymers constituted by a hydrophilic skeleton that bears some hydrophobic groups either randomly distributed along the chain (grafted or comb-like) or fixed at one or two extremities (telechelic). Telechelic polymers are linear chains containing associating “sticker” groups only at the chain ends, and are analogous to the triblock copolymers. The difference is in the shortness of the aliphatic “tail” group compared to the block size of typical triblocks. A telechelic polymer, therefore, bears features of both surfactants and block copolymers; it contains two surfactant-sized hydrophobic groups attached to a polymer-sized hydrophilic one. The telechelic polymers developed to date are most often based on poly(ethylene oxide) (PEO). Hydrophobic groups can be either aliphatic (with a number of methylene units ranging from 8 to 20), aromatic, or fluorinated. Such architectures lead to significant alteration of solution properties, often with water as solvent. In particular, it is well known that aqueous solutions exhibit shear-thickening and shear-thinning behaviors owing to the fact that hydrophobic groups associate pair-wise or into larger nano-domains, which act as temporary cross-links or chain extensions. This thickening behavior renders the polymers useful as additions that even at low loading levels, allow for adjustment of viscosity for purposes of processing, for example in coating applications, or in the formulation of products such as shampoo, facial cream, toothpaste and the like. Such self-assembly behavior of block copolymers and of hydrophobically modified polymers has been extensively studied as a building block approach to the processing of nanostructured materials beginning at the molecular level.
Several morphologies found in crew-cut aggregates made from two families of diblock copolymers, polystyrene-b-poly(acrylic acid) (PS-b-PAA) and polystyrene-b-poly(ethylene oxide) (PS-b-PEO), in dilute solution have been described. As the soluble PAA or PEO blocks are made progressively shorter, the morphology of the aggregates changes from spherical to rodlike to lamellar or vesicular and finally to large compound vesicles (LCVs) and large compound micelles The synthesis, characterization, and rheological behavior of a concentration-series of PEG end-capped with hydrophobic fluorocarbon groups has also been disclosed. Further the synthesis data on the aggregation of silsesquioxane-based amphiphiles; the cubic-shaped spherosilsesquioxane, 1-(1,ω-propylenemethoxy)oligo(ethylene oxide)-3,4,7,9,11,13,15-heptahydridopentacyclo[9.5.13.9.15.15.17.13]octasiloxane has been described. However, these silsesquioxane-based amphiphiles were monosubstituted.
To date, amphiphilic telechelics incorporating polyhedral oligosilsesquioxane (POSS) macromers have not been described. Such POSS macromers can represent interesting building units for the construction of organic-inorganic hybrid structures as compared to other hydrophobic groups, such as the linear aliphatic, aromatic, or fluorinated groups previously investigated. Amphiphilic telechelics having a hydrophobic, bulky, and well-defined dimensional property such that both end groups as has been proposed herein can contribute to self-assembly while contributing steric hindrance properties in the solution and melt state and have not been described. Moreover their partially inorganic composition offers the potential for conversion to ceramic (SiO2/SiC) nanostructures. Additionally, the new polymers yield control over polyethylene oxide crystallization which is of benefit to their application as solid polymer electrolytes for ion-conducting batteries, such as lithium-ion batteries.
It is an object of this invention to provide a method for synthesis of a series of amphiphilic telechelics incorporating POSS macromers as end groups of polyethyleneglycol (PEG) homopolymers.
It is a further object of the invention to provide new amphiphilic telechelics incorporating POSS macromers.
It is another object of the invention to provide new amphiphilic telechelics that incorporate POSS macromers as end groups of PEG homopolymers.
It is yet another object of the invention to provide new amphiphilic telechelics having predetermined hydrophilic/hydrophobic balance by use of PEG homopolymers of varying molecular weight.
A further object of the invention is to provide new amphiphilic telechelics which are useful as nonionic surfactants with enhanced thickening behavior.
A further object of the invention is to provide new amphiphilic telechelics which are useful as solid polymer electrolytes for ionic batteries.
Still a further object of the invention is to provide new amphiphilic telechelics which are useful to improve toughness of polymers that are compatible with poly(ethylene oxide), including but not limited to epoxy, poly(methylmethacrylate), poly(vinylacetate), poly(ethylmethacrylate), sulfonated polystyrene and polysulfone.